Abstract
AbstractGold nanoparticles coated with a poly(N‐isopropylacrylamide) (pNIPAM) shell undergo reversible dis/assembly below and above the critical temperature of 32 °C. Loading these particles into microdroplets at high density creates light‐driven artificial chromatophores. Triggering the nanoparticle assembly gives dramatic color changes from nanoparticle localization at the base of the droplets, resembling zebrafish melanophores. These reversible chromatophore states can be switched by both bulk and optical heating, explored here in individual microdroplets and in large cm2 areas of close‐packed droplets. Illuminating chromatophores off‐center with a tightly focused beam results in droplet locomotion via two separate mechanisms, Marangoni interfacial shear and gas bubble propulsion, depending on optical power.
Highlights
Motor proteins, such as myosin and kinesin, move functional components within cells
It was demonstrated that gold nanoparticles (NPs) can be reversibly dis/assembled with light using a poly(N-isopropylacrylamide) shell.[13,14]
We show that light-responsive artificial chromatophores can be created by loading microdroplets with Au@pNIPAM nanoparticles
Summary
Motor proteins, such as myosin and kinesin, move functional components within cells. In chromatophore cells, these molecular machines are used to reversibly manipulate pigments and nanocrystals to give strong changes in color and transparency. We show that light-responsive artificial chromatophores can be created by loading microdroplets with Au@pNIPAM nanoparticles. The microdroplets both limit the size of the nanoparticle clusters and can localize them to the oil-water interface. The localization of NPs to the liquid interface increases the local surface tension and creates a gradient across the microdroplet that drives Marangoni flows.
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